1. Field of the Invention
This invention relates to a water distributing hose for use in a trickle irrigation or drip irrigation system.
2. Background of the Prior Art
The present invention relates to irrigation systems particularly adapted for the surface or subsurface watering of long runs of crops, whether on greenhouse benches or in the field, and more specifically relates to a trickle irrigation system wherein the water is allowed to discharge slowly, directly at the desired point of application, normally about the base of the plants.
It has long been recoqnized that an efficient means is needed for applying water to crops, particuarly fied crops, at or below surface leve. Since at least as early as 1911 attempts have been made to solve the problems associated with the efficient distribution of water at or below soil level in view of, among other advantages, the substantial saving in water which can be achieved as compared to the conventional overhead sprinkling systems. Recent innovations have been directed to the concept of trickle irrigation. As an example, in row crops, it is only necessary to irrigate the rows and not the entire field. Such a limiting of the watering to the rows by trickle irrigation can effect a water saving of approximately 40 to 50 percent. As the need for food for the world's expanding population increases and water shortages become more acute, such savings will become increasingly more important. In this connection, trickle irrigation is especially significant because it delivers water at or below the surface and provides for a siqnificant conservation of water.
Since there is considerably less water used in trickle irrigation, it is important that the water be directed precisely to the plant's root area. The flow from some known prior art hoses comes out in a tiny squirt, which can be blown by the wind so that sometimes it does not uniformly wet the area next to the plant row. When an irrigation hose is located on top of the soil it is often twisted slightly by the contour of the soil. This causes the squirt to come out at different angles. The water from some of the squirts could fall next to the plant row and other squirts would be directed between the rows of plants leaving some root areas dry.
When the irrigation hose is used under a plastic mulch, as is frequently done, the flow sometimes squirts against the underside of the plastic mulch which deflects the water and causes part of it to follow the underside of the plastic and run off into the isle between the plant rows. The squirt sometimes has enough force to cause a tiny washout on elevated beds so that water runs down the side of the bed into the isle rather than remaining on top of the bed surface and uniformly penetrating the entire bed.
To be practical, trickle irrigation must provide for the delivery of water at a slow uniform rate over long lengths or runs of hose. In the past, various trickle irrigation systems have been tried, including pipes with small holes, pipes with various types of small outlet members, pipes with small tubes for outlets, plastic pipes with slits, tubes which ooze water through the wall, and hoses which ooze water through a sewn seam. Each type has depended on a small orifice, low pressure, friction created in a long outlet member such as a tube, or a combination of these to limit the flow through each individual outlet. However, there are disadvantages associated with each such known system. For example, the use of extremely small orifices such as holes, slits, or the like, tend to clog easily. Tube outlets and special outlet members are relatively expensive to produce and ship, particularly when considering the large quantities required. In addition, low pressure systems and tubes which provide for an oozing of the water through the wall are not capable of producing a uniform flow along the length of the hose or the like, particularly on sloping runs.
Since drip irrigation hoses are commonly made with wall thicknesses ranging from 0.003" to 0.030", the hoses are sometimes subject to damage from ants. When this occurs, ants have been known to go through the main wall of the hose, but usually they will chew around the edges of existing discharge openings, enlarging them, sometimes to several times their original diameter. In previous double chamber hoses, this causes the hose to have a heavy water flow at the enlarged discharge opening and a much lower flow in other nearby openings, resulting in a non-uniform irrigation.
One water distributing hose which has met with success is that disclosed in U.S. Pat. No. Re. 28,095, reissued July 30, 1974 to Chapin. In the reissue patent, a water distributing hose is shown in the context of a trickle irrigation system. The hose shown in FIG. 3 basically comprises an outer tubular wall and an inner wall spaced interiorly from the outer wall defining an inner tubular member. Both walls are perforated with the outer wall having a greater number of openings. The inner tube functions so as to carry water along the full length of the hose and maintain, to a substantial degree, the uniform pressure thereof. The water discharges through the inner wall openings and subsequently flows to and through the outer wall openings for a trickle discharge therefrom. Although the performance of this hose has been excellent, there is, nevertheless, always a need for improved performance. The present invention is directed toward filling that need while at the same time minimizing the disadvantages described above in connection with known systems.